The extraction of cobalt from weakly acidic solutions with di-(2-ethylhexyl) phosphoric acid (D2EHPA) in various low polar diluents such as benzene, toluene, o-xylene, m-xylene, n-heptane, cyclohexane and n-heptanebenzene mixtures was studied.
The extraction efficiency decreased in the following order, n-heptane>cyclohexane>m-xylene>oxylene>toluene>benzene and this order was in a good agreement with the order of solubility parameters of diluents. When n-heptane and cyclohexane as diluents were used, the extent of the salting-out effect was smaller in comparison with other diluents. When n-heptane and cyclohexane as diluents were used, Co-D2EHPA polymer were formed in low loading ratio in comparison with other diluents.
Meanwhile, when n-heptane-benzene mixtures as diluents were used, the extraction efficiency, the extent of salting-out effect and the formation of Co-D2EHPA polymer were changed consecutively by changing the composition of n-heptane-benzene mixtures.

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In order to investigate the flocculation and dispersion phenomena of fine particles in aqueous suspension, particle size distribution analyses of suspended particles were performed using the mixed suspension prepared by the mixtures of various proportion of quartz and fluorite samples whose contents of fine particles are different. The heteroflocculation phenomena of quartz and fluorite particles were observed in the mixed suspensions. We propose a possible model of heteroflocculation occuring in suspensions of mixtures of various proportions of quartz and fluorite, and illustrate the model schematically (Fig. 11 in the text). In the case of a suspension composed of uniform particles size D_S of quartz and fluorite, the model is represented as follows. Assume the suspension is a mixture of each suspension of quartz and fluorite whose concentrations are C_q and C_f, and volumes are V_q and V_f, respectively. The numbers of particles in the suspension of quartz N_q and fluorite N_f, are represented by C_q×V_q and C_f×V_f, respectively. When the value of C_q is smaller than that of C_f, the value of V_q must be larger than that of V_f to achieve the condition of N_q=N_f, which corresponds to the case of a mixture of equal ratio of quartz and fluorite. The phenomena occuring in suspensions of mixtures of various proportions of quartz and fluorite may be explained by the above modification of the model proposed in the 1st report for the mixture of equal ratio of quartz and fluorite.

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